U.S. patent number 6,573,671 [Application Number 09/905,485] was granted by the patent office on 2003-06-03 for fan reliability.
This patent grant is currently assigned to Dell Products L.P.. Invention is credited to Adolfo S. Montero, Hasnain Shabbir.
United States Patent |
6,573,671 |
Montero , et al. |
June 3, 2003 |
Fan reliability
Abstract
A computer system or other electronic system includes a
plurality of cooling fans configured to operate in parallel. The
cooling fans are operated in a manner to decrease the operating
time of a fan. The cooling fans can alternate in operation. Thus,
operating time is more equally divided between the two cooling fans
and the hours of operation and number of rotations of the fans is
more nearly equal. In an embodiment to reduce noise, two fans run
at a lower speed instead of one fan at a higher speed. In an
embodiment, a fan operates with a reduced speed which maintains a
desired operating temperature. In an embodiment a thermal table is
stored in BIOS (basic/input output system).
Inventors: |
Montero; Adolfo S. (Austin,
TX), Shabbir; Hasnain (Round Rock, TX) |
Assignee: |
Dell Products L.P. (Round Rock,
TX)
|
Family
ID: |
25420918 |
Appl.
No.: |
09/905,485 |
Filed: |
July 13, 2001 |
Current U.S.
Class: |
318/53;
G9B/33.041; G9B/33.038; 318/471; 318/59; 318/66 |
Current CPC
Class: |
H01H
83/04 (20130101); G06F 1/206 (20130101); G11B
33/142 (20130101); G11B 33/144 (20130101); F04D
27/004 (20130101); F04D 25/166 (20130101); H05K
7/20727 (20130101); H05K 7/20836 (20130101); Y02B
30/70 (20130101) |
Current International
Class: |
H01H
83/00 (20060101); G06F 1/20 (20060101); G11B
33/14 (20060101); H01H 83/04 (20060101); H05K
7/20 (20060101); H02P 005/46 () |
Field of
Search: |
;318/34,41,51,53,59,66,68,69,77,105,112,471 ;310/62,63
;388/934 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ro; Bentsu
Attorney, Agent or Firm: Baker Botts L.L.P.
Claims
What is claimed is:
1. A computer system, comprising: a central processing unit
("cpu"); a first cooling fan; a second cooling fan; a controller
coupled to the cpu and to the first and the second cooling fan, the
controller having an input for receiving a temperature signal
indicative of a temperature of the cpu, a first output for
providing a first control signal to the first fan, and a second
output for providing a second control signal to the second fan,
wherein the controller operates to sequentially: start the first
fan; stop the first fan; start the second fan; stop the second fan;
and start the first fan.
2. The computer system as recited in claim 1, further comprising: a
temperature sensor coupled to the cpu for providing a temperature
signal to the controller; and a basic input/output operating system
(bios), the bios further comprising: a thermal table, the thermal
table identifying a temperature at which the first control signal
is sent from the controller to the first cooling fan.
3. The computer system as recited in claim 2, wherein the thermal
table further identifies a temperature at which a stop signal is
sent from the controller to the first cooling fan.
4. The computer system as recited in claim 1, further comprising: a
temperature sensor coupled to the cpu for providing a cpu
temperature signal to the controller; and a set of software
instructions stored in a memory of the computer system effective to
identify a temperature at which the first control signal is sent
from the controller to the first cooling fan.
5. The computer system as recited in claim 4, wherein a thermal
table further identifies a temperature at which a stop signal is
sent from the controller to the first cooling fan.
6. The computer system as recited in claim 1, wherein the
controller sends a speed signal to the first cooling fan, the speed
signal controlling the speed of the first cooling fan to a first
speed, wherein the first cooling fan operating at the first speed
produces less noise than the first cooling fan operating at a
second speed.
7. In a computer system, a method of operating at least a first
cooling fan and a second cooling fan, so as to more evenly
distribute the running time of the fans, the method comprising:
coupling a temperature sensor to a central processing unit ("cpu");
coupling a temperature control signal from the temperature sensor
to an input of a fan controller; coupling a first fan control
output of the fan controller to the first fan; coupling a second
fan control output of the fan controller to the second fan; and
causing the controller to operate so as to sequentially: start the
first fan; stop the first fan; start the second fan; stop the
second fan; and start the first fan.
8. The method as recited in claim 7, further comprising: storing a
basic input/output operating system (bios) in a memory of the
computer system; and the bios further comprising a thermal table,
the thermal table identifying a first temperature at which a first
start signal is sent to the first cooling fan.
9. The method as recited in claim 8, wherein the thermal table
identifies a second temperature at which a first stop signal is
sent to the first cooling fan.
10. The method as recited in claim 9, wherein the thermal table
identifies a third temperature at which a second start signal is
sent to the second cooling fan.
11. The method as recited in claim 8, wherein the thermal table
identifies a first temperature and a first speed, wherein a first
integrator circuit sends a first speed signal to the first cooling
fan.
12. The method as recited in claim 11, wherein the thermal table
identifies a second temperature and a second speed, a second
integrator circuit sends a second speed signal to the second
cooling fan, the second speed signal identifies a second operating
speed for the second cooling fan, wherein the first cooling fan
operating at the first speed and the second cooling fan operating
at the second speed produces less noise than the first cooling fan
operating at a speed higher than the first speed.
13. An electronic system, comprising: a central processing unit
("cpu"); a first cooling fan; a second cooling fan; a controller
coupled to the cpu and to the first and the second cooling fan, the
controller having an input for receiving a temperature signal
indicative of a temperature of the cpu, a first output for
providing a first control signal to the first fan, and a second
output for providing a second control signal to the second fan,
wherein the controller operates to sequentially: start the first
fan; stop the first fan; start the second fan; stop the second fan;
and start the first fan.
14. The electronic system as recited in claim 13, further
comprising: a temperature sensor coupled to the cpu for providing a
temperature signal to the controller; and a basic input/output
operating system (bios), the bios further comprising: a thermal
table, the thermal table identifying a temperature at which the
first control signal is sent from the controller to a first cooling
fan.
15. The electronic system as recited in claim 14, wherein the
thermal table further identifies a temperature at which a stop
signal is sent from the controller to the first cooling fan.
16. The electronic system as recited in claim 14, wherein the
thermal table further identifies a temperature at which the first
control signal is sent to the second cooling fan.
17. The electronic system as recited in claim 14, wherein the
thermal table further identifies a temperature at which a stop
signal is sent to the second cooling fan.
18. The electronic system as recited in claim 14, wherein the
thermal table identifies a temperature at which a first signal is
sent to the first cooling fan for the first cooling fan to operate
at a first speed, the first speed is less than a second speed,
wherein the first cooling fan operating at the first speed produces
less noise than operating at the second speed.
19. A computer system, comprising: a cpu, a memory operably coupled
to the cpu; a first cooling fan; a second cooling fan; a controller
coupled to the first cooling fan and the second cooling fan; and
means for alternating operation of the first cooling fan and the
second cooling fan.
20. The computer system as recited in claim 19, further comprising:
means for operating the first cooling fan at a first speed, wherein
the first speed is less than a second speed, wherein operating the
first cooling fan at the first speed increases the operating life
of the first cooling fan.
21. The computer system as recited in claim 19, further comprising:
means for operating the first cooling fan at a first speed to
increase the reliability of the computer system.
22. The computer system as recited in claim 19, further comprising:
means for operating the first cooling fan at a first speed and
means to operate the second cooling fan at a second speed to reduce
noise produced by the first cooling fan operating at a third
speed.
23. The computer system as recited in claim 19, further comprising:
means for operating the first cooling fan and the second cooling
fan in response to information related to a temperature of the
cpu.
24. A computer program product encoded in computer readable media,
comprising: a set of instructions configured to alternate operation
of a first cooling fan and a second cooling fan.
25. The computer program product as recited in claim 24, further
comprising: a set of instructions configured to control a speed of
operation of the first cooling fan to increase the reliability of
an electronic system.
26. The computer program product as recited in claim 24, further
comprising: a set of instructions configured to reduce the
operating frequency of a cpu, the reduction in operating frequency
of the cpu reducing heat generated by the cpu.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of improving the
reliability of a computer or other electronic system. More
specifically, the present invention relates to alternating
operation of cooling fans to improve reliability of the fans and
the system.
2. Description of the Related Art
Computer systems are information handling electronic systems which
can be designed to give independent computing power to one user or
a plurality of users. Computer systems may be found in many forms
including, for example, mainframes, minicomputers, workstations,
servers, personal computers, internet terminals, and notebooks.
Computer systems include desk top, floor standing, rack mounted, or
portable versions. A typical computer system includes at least one
system processor, associated memory and control logic, and a number
of peripheral devices that provide input and output for the system.
Such peripheral devices may include display monitors, keyboards,
mouse-type input devices, floppy and hard disk drives, CD-ROM
drives, printers, network capability cards, terminal devices,
modems, televisions, sound devices, voice recognition devices,
electronic pen devices, and mass storage devices such as tape
drives, CD-R drives, or DVDs.
Compared to currently manufactured desk top and laptop computers,
early computers consumed relatively little power and relied on
convective cooling. Convective cooling allows components to
dissipate heat through contact with ambient air. However ambient
air is not a particularly efficient conductor of heat. Ambient air
can become trapped within a computer casing and act as an insulator
instead of a conductor. Trapped ambient air acting as an insulator
can increase the operating temperature of a computer. Thus, later
computers included fans to draw air from the atmosphere and direct
the air into the computer enclosure.
Computer systems continue to increase in operating speed and
decrease in size. As operating frequencies increase power
consumption also increases. Increased power consumption increases
heat generated. An increase in heat generated increases operating
temperatures, particularly of the central processing unit (cpu). As
computer systems decrease in size the heat generated is confined to
a smaller space. Therefore, in smaller faster systems such as
laptops, more heat is confined to a smaller space. Confining more
heat to a smaller space causes much higher surface temperatures of
all components, particularly the heat generating components.
Dissipation of heat through convection or other means allows
internal components to remain within their normal operating
temperature range. For the reasons described in the preceding
paragraph, ambient convection is frequently insufficient to provide
sufficient cooling. However, air moving across the surface of a
component raises the convective heat transfer coefficient for the
surface of the component. Increasing the convective heat transfer
coefficient for a component increases the heat transfer from the
component to the atmosphere and decreases the temperature of the
component. Therefore, designers and manufacturers turn to forced
convection (also referred to as "forced air cooling") to provide
sufficient cooling capacity.
A cpu consumes more electrical power than any other component in a
conventional desktop or laptop computer. A significant portion of
the electrical power consumed by the cpu is dissipated as heat
during operation of the computer. Thus, the cpu tends to produce
more heat than any other component within a computer system. A heat
sink can be provided to increase the area of the cpu available for
convective cooling and to redce the thermal resistance between the
cpu and the ambient environment. Convective cooling enhanced by a
heat sink may be sufficient in limited operating conditions. More
generally, at least one dedicated cooling fan is provided to force
ambient air across a cpu surface. In many cases another cooling fan
is provided to move air across the surface of other components
within the computer chassis.
Providing multiple fans introduces problems into the operation of a
computer system. In many cases the operating life of a cooling fan
is less than the projected operating life of the computer system.
Providing multiple fans increases the probability of failure of a
single fan. Failure of a fan can lead to failure of the computer
system and decreased customer satisfaction.
U.S. Pat. No. 5,168,424 to Bolton et al. titled "Multi Unit
Electrical Apparatus with Dual Inlet Fan Positioned Opposite Unit
Bays" (also referred to as "Bolton") teaches an electrical system
having fans which can be dedicated to various components within the
system. However, Bolton does not teach multiple fans dedicated to
one component.
Multiple fans can also increase operating noise of a system. When
both fans are operating they may interact, in some cases even
operating at resonant frequency. Increased noise causes distraction
and also causes decreased customer satisfaction. Multiple fans
operating simultaneously can be cooling a component which requires
cooling from only one fan, thus increasing manufacturing cost
without benefit.
U.S. Pat. No. 5,687,079 to Bauer et al. titled "Method and
Apparatus for Improved Control of Computer Cooling Fan Speed" (also
referred to as "Moss") teaches controlling fan speeds to prevent
audible noise from being produced by the fans. However, Bauer does
not teach alternating operation of cooling fans. Nor does Bauer
teach controlling fan speeds in response to cpu temperature or
internal temperature of a computer system.
U.S. Pat. No. 5,546,272 to Moss et al. titled "Serial Fan Cooling
Subsystem for Computer Systems" (also referred to as "Moss")
teaches using fans in series to cool components of a computer
system. However, Moss does not teach alternating operation of the
fans to increase fan reliability. Nor does Moss teach varying the
speed of a fan to increase fan reliability or to reduce noise.
U.S. patent application Ser. No. 09/537,159 filed on Mar. 29, 2000
listing Stephen J. Davies, Jil M. Bobbitt and Jason D. Tunnell as
inventors, titled "Series Fan Speed Control System," now U.S. Pat.
Ser. No. 6,396,688 (also referred to as "Davies") again teaches
cooling a computer component using fans in series. Davies also
teaches switching from one fan to another if a fan fails. However,
Davies teaches two fans operating in series, not in parallel.
However, in a series configuration if one fan fails the remaining
fan must pull air through or push air past the disabled fan. Nor
does Davies teach alternating fans to increase operating
reliability of the system. Nor does Davies teach controlling fan
speed to increase system reliability or reduce noise.
SUMMARY OF THE INVENTION
In accordance with the present disclosure an apparatus and a method
are taught to increase the reliability of a computer system or
other electronic system. A computer system includes a plurality of
cooling fans configured to operate in parallel. The cooling fans
are operated in a manner to increase the reliability of the fans.
Thus the fans have an extended life. The increased life of the
cooling fans increases the reliability of the system.
The cooling fans are operated in a manner to decrease the operating
time of a fan. The cooling fans can alternate in operation. Thus,
operating time is more equally divided between the two cooling fans
and the hours of operation and number of rotations of the fans is
more nearly equal. In an embodiment, a fan operates with a reduced
speed which maintains a desired operating temperature. In an
embodiment to reduce noise, two fans run at a lower speed instead
of one fan at a higher speed. In an embodiment a thermal table is
stored in BIOS (basic/input output system).
The foregoing is a summary and this contains, by necessity,
simplifications, generalizations and omissions of detail;
consequently, those skilled in the art will appreciate that the
summary is illustrative only and is not intended to be in any way
limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention may be better understood, and its numerous
objects, features and advantages made apparent to those skilled in
the art by referencing the accompanying drawings. The use of the
same reference number throughout the several figures designates a
like or similar element.
FIG. 1 shows a flow diagram of a logical sequence to alternate
operation of two cooling fans.
FIG. 2A is a block diagram of one example of a computer system
according to the present invention. FIG. 2B is a block diagram of
the computer system as shown in FIG. 2A according to one embodiment
of the disclosure.
FIG. 3 shows a line diagram of a circuit to operate two cooling
fans in a computer system such as the exemplary computer system
shown previously in FIG. 2A and FIG. 2B.
FIG. 4 is a block diagram of one example of a computer system, such
as the exemplary computer system shown in FIG. 2A, enabling the
feature of the disclosure previously shown in FIG. 3.
FIGS. 5A and 5B are circuit diagrams of integrator circuits
according to one embodiment of the invention.
DETAILED DESCRIPTION
The following sets forth a detailed description of a mode for
carrying out the invention. The description is intended to be
illustrative of the invention and should not be taken to be
limiting. The disclosure describes a computer system including at
least two fans configured to operate in parallel. Cooling air from
the fans can be dedicated to cooling a single component, such as a
cpu. The operation of the fans is controlled to increase the
operating life of the computer system. Increasing the operating
life of the computer system is accomplished by reducing the
operating time of a fan. In many cases, one fan starts first during
each cycle. In the prior art, one fan will accumulate the most
operating hours and typically will fail before any other fan.
According to one embodiment, the operation of the fans will
alternate. Alternating operating the fans will preclude one fan
from accumulating a disproportionate number of operating hours and
failing prematurely.
In an embodiment further described in FIG. 1 (below), a computer
system has two fans; fan A and fan B. In normal operation one fan,
for example fan A, can operate until it has provided sufficient
cooling and it is no longer needed. When it is no longer needed,
fan A can be turned off. In earlier computer systems, when
additional cooling was required, the same fan, fan A, would again
be started. In this scenario fan B would only be used if fan A did
not provide sufficient cooling. Thus, under earlier operational
configurations fan B could be expected to operate less often than
fan A. Thus, fan A would be expected to accumulate more operating
hours than fan B and thus fan A would be expected to fail before
fan B.
According to one enablement of the invention, a temperature sensor
monitors the cpu temperature. If no fan is operating and the
temperature of the cpu increases above a predetermined point, a
signal is generated to start operation of a fan. In the exemplary
operational configuration described by this disclosure, the signal
will start fan A or fan B alternately. Thus, fan B can start and be
operated alone, unless fan A is needed for additional cooling.
Thus, the time of operation of each fan can be reduced over the
life of the computer, extending the life of each fan. In some
circumstances operation of both fans may not be necessary to
provide sufficient cooling. Another enablement of the invention
contemplates reducing the operating speed of a fan to extend the
operating life of the fan.
For example, in an environment having a low ambient temperature,
one fan may have the capacity to provide sufficient cooling air. To
accommodate various operating conditions, the speed of a single fan
(or pair of fans) may increase or decrease. In one embodiment, the
operating speed of a fan can be controlled depending on the
temperature of the cpu. Decreasing the average operating speed of
each fan decreases the revolutions of each fan during a specific
period of time. Decreasing the total revolutions of each fan for a
given time increases the operating life of each fan. In yet another
embodiment, the number of fans operating can be controlled to
satisfy cooling or noise requirements.
If only one fan is operating and the temperature of the cpu
continues to increase, the invention contemplates various
alternatives. In one approach, illustrated in Table 1 below, the
speed of the operating fan is increased. In this scenario, if
increasing the speed of the operating fan does not stabilize or
reduce the cpu temperature, the speed of the operating fan can
again be increased. Alternatively, the second fan can be started.
Speed and operation of each fan can be controlled in accordance
with an algorithm stored in system BIOS (basic input/output
operating system). The algorithm can be instantiated in a number of
suitable means, including a table. For example, Table 1, Table 2
and Table 3 below, provide examples of a BIOS thermal table.
Referring to FIG. 1, a sequence is illustrated in which only one
fan operates at a time. This sequence can begin a circuit or other
device initiates a start request for a fan. This instruction
corresponds to one fan start request 100 as represented in FIG. 1.
If a fan start request is received, the logical sequence proceeds
to decision 120, last fan =fan A. (If a fan start request is not
received then the logical sequence proceeds to logical event 150,
fan off request.) In decision 120 the last fan operating is
identified. If the last fan operating was fan A then the process
continues to logical event 130. In logical event 130, a signal is
generated to start fan B. Thus, the operation of fan A and fan B
are alternated, and the operating time of each of the fans is
consequently reduced.
If logical decision 120 determines the last fan operating was fan
B, then the process continues to logical step 140. In logical step
140 a signal is generated to start fan A. Thus, again the operation
of fan A and fan B are alternated, and the operating hours of each
of the fans is reduced. From logical step 140 (and logical step 130
described in the preceding paragraph) the process continues to
logical step 150, fan off request. Fan off request 150 issues a
stop command to either operating fan, fan A or fan B. From logical
step 150 the process continues to logical step 110, initially
chosen as the beginning point.
FIG. 2A is a block diagram of an exemplary computer system 200 that
may be found in many forms, including, e.g., mainframes,
minicomputers, workstations, servers, personal computers, internet
terminals, notebooks, and embedded systems. Personal computer
("PC") systems, such as those compatible with the x86
configuration, include desktop, floor standing, or portable
versions. Exemplary computer system 200 includes a computer system
hardware unit that further includes a central processing unit
(sometimes referred to simply as processor") 210, associated main
memory 250, and a number of peripheral devices that provide I/O for
the system 200, and computer system software that runs on the
hardware unit. Exemplary computer system 200 is powered by a power
supply 214. Power supply 214 can include a voltage regulator, not
shown.
Peripheral devices often include keyboards 291, mouse-type input
devices 292, CD drive 264, and others not shown, including
monitors, floppy and hard disk drives, modems, printers, terminal
devices, televisions, sound devices, voice recognition devices,
electronic pen devices, and mass storage devices such as tape
drives or digital video disks ("DVDs"). The peripheral devices
usually communicate with the processor over one or more peripheral
component interconnect ("PCI") slots 266, universal serial bus
("USB") ports 275, or integrated device electronics ("IDE")
connectors 276. The PCI slots 266 may use a card/bus controller 265
to connect to one or more buses such as host bus 220, PCI bus 260,
and low pin count ("LPC") bus 280, with the buses communicating
with each other through the use of one or more hubs such as
graphics controller memory hub 240 and I/O controller hub 270.
Typical systems such as exemplary system 200 often include network
interface cabling slots 298 to accommodate network cards that
mediate between the computer and the physical media over which
transmissions to and from system 200 travel. USB ports 275 and IDE
connectors 276 may connect to one or more of the hubs 240, 270. The
hubs may communicate with each other through the use of one or more
links such as hub link 290.
Many I/O devices can also be accommodated by parallel port 293 and
serial port 294 that are also coupled to controller 287 that is in
turn coupled to a LPC bus 280. In one enablement of a exemplary
computer system 200, controller 287 can be referred to as LPC
controller 287. Typical computer systems often include a graphics
card 231 coupled to a graphics memory controller hub 240 by a
graphics bus 235 and a main memory 250 coupled to a graphics memory
controller hub 240 by a memory bus 230. Finally, a typical computer
system also includes software modules known as BIOS code. BIOS code
is either copied from an external medium such as a CD to, or stored
on, the memory area 281 in firmware hub 286.
Referring to FIG. 2B, in one embodiment fan 330 and fan 340 can be
installed in a computer system as shown. An example of a fan
suitable for this application include part number GM0503PEB1-8 L2.M
as provided by Sunon of Taiwan. (For more information on the
manufacturer refer to website www.Sunon.com.) Fan 330 receives a
control signal 281, and fan 340 receives a control signal 291 from
controller 287 as shown.
FIG. 2B is a line diagram of a circuit that controls two fans in an
operational configuration to increase the reliability of the
computer system. Temperature sensor 207 detects the surface
temperature signal of processor 210 via sense line 205. In one
embodiment, temperature sensor 207 translates the analog signal
into a digital signal representing temperature. Temperature sensor
207 can transmit the digital temperature data signal to controller
287 via SM bus 230. An example of a temperature sensor suitable for
this application is part number ADI 1032, available from Analog
Devices, Inc. of Norwood, Mass.)
In one embodiment, the cpu has an internal temperature sensor. The
internal cpu temperature can be detected by (external) temperature
sensor 207. In one embodiment the external sensor converts the
temperature signal received from the cpu from analog to
digital.
Controller 287 can issue start signals to fan 330 and fan 340 via
signals 281 and 291. In an embodiment, tachometer 331 and 341 can
communicate speed signals from fan 330 and fan 340 respectively, to
controller 287. In an embodiment, controller 287 can use the speed
of fan 330 and 340 as input to a logic sequence (such as the logic
sequence shown in FIG. 1) to control fan 330 and fan 340.
The start signal generated by controller 287 can be derived from
information stored in a temperature table. A temperature table can
be stored in a memory of a computer system, such as memory area 281
of exemplary computer systems 200 or 202. The temperature table can
control signal 281 and signal 291 to start fan 330 and 340
alternately. As shown in Tables 1, 2 and 3 below, the temperature
table can modify signal 281 and signal 291 to control the fan speed
of fan 330 and 340. In Tables 1, 2 and 3 it is intended that fan
330 and fan 340 alternate operation. Thus when used in Table 1, 2
or 3 below, "fan A" can refer to either fan 330 or fan 340 and "fan
B" can refer to either fan 330 or fan 340.
TABLE 1 Fan A Status Fan B Status Temperature Off Off 72.degree. F.
falling Low Off 72.degree. F. rising/62.degree. F. falling Medium
Off 82.degree. F. rising/65.degree. F. falling High High 92.degree.
F. rising/70.degree. F. falling Shutdown Shutdown 96.degree. F.
Under the operational configuration as contemplated by Table 1,
when the cpu temperature is less than 72.degree. F., both fans are
off. When the cpu temperature rises above 72.degree. F., fan A
begins operating at a low speed. If the cpu temperature again
increases and rises above 82.degree. F., fan A begins to operate at
a medium speed. If the cpu temperature rises above 92.degree. F.,
fan A increases speed and operates at high speed. Fan B also begins
to operate and operates at high speed. According to the
configuration described in Table 1 if the temperature of the cpu
rises above 96.degree. F. the computer system shuts down. Shutting
down the computer system limits damage to the computer system from
localized hot spots caused by insufficient cooling. However, Table
1 is an example and is not limiting. Neither the temperatures
listed nor the fan status is fixed. Temperature and fan status can
be changed according to system or other requirements.
Table 1 also represents a configuration of operation of the fans as
the temperature of the cpu is falling. For example, if both fans
are operating at high speed and the temperature of the cpu can, in
some circumstances begin to decrease. In this configuration if the
cooling air provided by the fans operating at high speed exceeds
the volume of air required to reduce the temperature of the cpu,
the temperature of the cpu can begin to decrease (depending on cpu
power requirements and other variables). In this configuration if
the temperature of the cpu falls below 70.degree. F., fan B can be
shutdown and the speed of fan A can be reduced from high to
medium.
Similarly, if the temperature of the cpu is 80.degree. F. and if
fan A is operating at medium speed the temperature of the cpu in
some circumstance can decrease. When the temperature of the cpu
decreases from 80.degree. F. below 65.degree. F., the operating
speed of fan A will decrease from medium to low as represented by
Table 1, above. Other fan speeds and operational configurations are
given in Table 1 for other ranges of falling temperatures.
In another example, Table 2 below provides an alternate BIOS
thermal table. Table 2 illustrates that both fan life and fan
operating noise can be considered when constructing a bios thermal
table. For example, Table 1 and Table 2 provide different operating
configurations if the operating temperature of the cpu rises above
82.degree. F. In the configuration described in Table 1, if the
temperature of the cpu rose above 82.degree. F., fan A would
operate at a medium speed. However one fan, fan A, operating at
high speed may produce more noise than two fans operating at low
speed. Thus Table 2 provides an alternate operating configuration
than Table 1 to reduce noise.
In the configuration described in Table 2, if the operating
temperature of the cpu rises above 82.degree. F., fan A and fan B
both begin operate at low speed. In this configuration the
simultaneous operation of fan A and fan B at low speed is intended
to reduce the total noise produced by both fans and thus reduce
consumer dissatisfaction. Again, Table 2 is not limiting.
Configurations other than the configuration described in Table 2
are possible to reduce operating noise.
TABLE 2 Fan A Status Fan B Status Temperature Off Off 72.degree. F.
falling Low Off 72.degree. F. rising/62.degree. F. falling Low Low
82.degree. F. rising/65.degree. F. falling High High 92.degree. F.
rising/70.degree. F. falling Shutdown Shutdown 96.degree.
F.degree.
Any configuration of a thermal table to reduce operating noise of
the fans is within the spirit and scope of an enablement. Another
example of an embodiment of a temperature table is given below in
Table 3.
As shown in Table 3 (below) a thermal table can perform other
functions. An example of a function which can be performed by the
thermal table is to reduce the operating frequency of the cpu.
Reducing the operating frequency of the cpu can reduce the power
consumed by the cpu. Reducing the power consumed by the cpu reduces
heat generated which is expected to reduce surface temperature.
TABLE 3 Fan A Status Fan B Status Temperature Off Off 72.degree. F.
falling Low Off 72.degree. F. rising/62.degree. F. falling Medium
Off 82.degree. F. rising/65.degree. F. falling High High 92.degree.
F. rising/70.degree. F. falling High; throttle 25% High; throttle
25% 96.degree. F. rising/90.degree. F. falling High; throttle 50%
High; throttle 50% 99.degree. F. rising/92.degree. F. falling
Shutdown Shutdown 102.degree. F..degree.
In the temperature region below 92.degree. F., Table 3 is similar
to Table 1. Above 92.degree. F. Table 3 provides information upon
which to generate a signal to reduce the operating frequency of the
cpu. More specifically, if the operating temperature of the cpu is
92.degree. F. and both fans (fan A and fan B) are operating at full
speed no excess fan cooling capacitiy is available. In this
scenario if the temperature of the cpu continues to increase and
exceeds 96.degree. F. the operating frequency of the cpu is
decreased by 25%. Similarly, if the cpu temperature continues to
increase and exceeds 99.degree. F. the operating frequency of the
cpu is again decreased to 50%. Still referring to Table 3, if the
operating frequency of the cpu has been decreased to 50% and if the
temperature of the cpu begins to decrease and falls from above
99.degree. F. to below 96.degree. F. then the operating speed of
the cpu will increase from 50% to 75%.
Again, Table 3 is illustrative and is not limiting. Neither the
operational configurations nor the corresponding temperatures shown
in Table 3 are limiting. Tables 1, 2 and 3 are provided as examples
only. A temperature table such as Table 1, Table 2 or Table 3 can
operate in conjunction with a software module to alternate
operation of the fans as described previously (refer to FIG.
1).
As shown previously (refer to Table 1, Table 2 and Table 3) the
manner in which the operation of fan 330 and 340 can be controlled
is not limited. In the manner described the operating speed and
operating time of fan 330 and fan 340 can be reduced thus
increasing the reliability of the fans and the computer (or other
electronic) system can be increased.
FIG. 4 shows a line diagram of a circuit which can control two fans
in an operational configuration, such as an operational
configuration described in a temperature table. Temperature sensor
207 detects the surface temperature of processor 210 via sense line
205. Temperature sensor 207 and translates the analog signal into a
digital signal representing temperature. Temperature sensor 207 the
digital temperature data signal to controller 287 via SM bus 230.
Controller 287 can transmit the temperature via LPC bus 280 to hub
link 290 and host bus 220 to processor 210.
In the embodiment shown in FIG. 4, integrator circuit 335 and
integrator circuit 345 receive pwm signal 380 and pwm signal 390
from controller 287 which receives a temperature signal from
temperature sensor 207 (as previously shown in FIG. 2B). Controller
287 receives tachometer signals 331 and 341 (also referred to as
speed signals) from fan 330 and fan 340. Fan 330 and fan 340
receive analog signals from integrator circuit 335 and integrator
circuit 345.
Still referring to FIG. 4, integrator circuit 335 and integrator
circuit 345 receive digital pulse width modulation signals ("pwm")
380 and 390 from controller 287 as shown in FIG. 2B. Integrator
circuit 335 and integrator circuit 345 translate the digital pwm
signals to analog format. The analog signal (typically zero to five
volts) is used as a power supply to fan 330 and to fan 340. The
analog signal provides speed control by varying the amplitude of
the signal. In one embodiment a temperature table, (such as Table
1, 2 or 3 shown previously) defines pwm signals which the
integrator circuit translates to an analog voltage signal. A
temperature table can be stored in the memory of a computer system,
such as exemplary computer system 200. In an embodiment, the
temperature table can modify pwm 380 and pwm 390 to start fan 330
and 340 alternately. Similarly, the temperature table can modify
pwm 380 and 390 to control the fan speed of fan 330 and 340.
FIG. 5A is a circuit diagram of integrator circuit 335 according to
one embodiment of the invention. As shown in FIG. 5A, integrator
circuit 335 receives pwm 380 from controller 287 (previously shown
in FIG. 3). Integrator circuit 335 sends tachometer 331 signal to
controller 287. As shown in FIG. 5A, integrator circuit 335 sends a
signal to fan 330 (as shown in FIG. 3). FIG. 5B is a circuit
diagram of integrator circuit 345 of one embodiment of the
invention. As shown in FIG. 5B, integrator circuit 345 receives pwm
390 from controller 287. Integrator circuit 345 sends tachometer
341 signal to controller 287. As shown in FIG. 5B, integrator
circuit 345 sends a signal to fan 340 (as shown in FIG. 3).
Integrator circuits 335 and 345 translate pwm signals 380 and 390
from digital format to analog format. The analog signal (typically
zero to five volts) is used as a power supply to fans 340 and 360.
Thus, the integrator circuits provide speed control by varying the
amplitude of the signal. However, the integrator circuits shown in
FIGS. 5A and 5B are examples only and are not limiting. Other
circuits to translate the digital signal to an analog signal may be
used. Alternatively, the fans may be controlled without use of an
integrator circuit as shown previously in FIG. 2B.
The method disclosed is not restricted to a specific software,
software language or software architecture. Each of the steps of
the method disclosed may be performed by a module (e.g., a software
module) or a portion of a module executing on a computer system.
Thus, the above component organization may be executed on a laptop
computer (as previously shown in FIG. 2A) or a desk top computer
system. The method may be embodied in a machine-readable and/or
computer-readable medium for configuring a computer system to
execute the method. Thus, the software modules may be stored within
and/or transmitted to a computer system memory to configure the
computer system to perform the functions of the module.
The operations described above and modules therefor may be executed
on a computer system configured to execute the operations of the
method and/or may be executed from computer-readable media. The
method may be embodied in a machine-readable and/or
computer-readable medium for configuring a computer system to
execute the method.
While particular embodiments of the present invention have been
shown and described, it will be obvious to those skilled in the art
that, based upon the teachings herein, changes and modifications
may be made without departing from this invention and its broader
aspects. Therefore, the appended claims are to encompass within
their scope all such changes and modifications as are within the
true spirit and scope of this invention. Furthermore, it is to be
understood that the invention is solely defined by the appended
claims.
* * * * *
References